A 26-year-old woman with a single-dose methotrexate treatment for ectopic pregnancy (initial hCG 1,850 IU/L) presents at Day 7 with hCG 1,920 IU/L (rose by 4% from Day 4 value of 1,850). She is hemodynamically stable with no increase in abdominal pain. What is the correct interpretation and next management?
- A Treatment failure — hCG has not fallen >15% between Day 4 and Day 7; proceed to surgical management or second-dose MTX ✓
- B Expected response — hCG may rise in first 72–96 hours post-MTX before declining; monitor Day 7 vs Day 4 comparison
- C Treatment failure — any hCG rise after methotrexate is pathological; give second MTX dose immediately
- D Expected failure of single-dose protocol as initial hCG >2,000 IU/L; discharge and schedule follow-up in 2 weeks
Explanation
The single-dose methotrexate protocol (50 mg/m²) monitors hCG on Days 4 and 7 post-injection. Treatment success is defined as a ≥15% decline in hCG between Day 4 and Day 7. In this case, hCG rose from 1,850 to 1,920 IU/L (a 4% rise), which does NOT meet the ≥15% decline criterion — this indicates treatment failure. The initial rise in hCG in the first 72–96 hours after MTX (B) refers to the rise between Day 1 and Day 4, which is expected and does NOT predict failure; this is the 'Day 1 to Day 4 rise' that is normal. By Day 7, if the fall from Day 4 is <15%, the patient should receive a second MTX dose or surgery. Since Day 7 vs Day 4 shows a rise rather than a fall of ≥15%, the answer is option A.
Reference: Williams Obstetrics, 26th ed.
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Written and medically reviewed by the StethoPrep medical team.